A test apparatus that tests a device under test is provided. The test apparatus includes a test module that provides a test signal to the device under test. The test apparatus includes: a test module that provides a test signal to the device under test; a measuring instrument that measures a reference parameter including at least one of a reference voltage, a reference resistance and a reference current included in the test module; and a control device that controls the test module and the measuring instrument. By executing a diagnostic program that diagnose the plurality of test modules by using the measuring instruments, the control device to function as: a target diagnostic section that diagnoses a target test module; an acquirement section that acquires measuring instrument identification information indicative of the kind of the measuring instrument provided in the test apparatus; a measurement processing section provided for each kind of the measuring instruments and executed on the control device that issues a command to cause the measuring instrument to measure the value of the reference parameter of the test module to the measuring instrument and receives a measurement result of the reference parameter from the measuring instrument; and a switching section that calls the measurement processing section corresponding to the measuring instrument identified by the measuring instrument identification information in response to receiving the call to instruct to measure the value of a reference parameter included in the test module, executes the same and returns the measurement result of the reference parameter to the target diagnostic section.